brickboy

My dad's Octavia 1.6 petrol has developed a fuelling problem (multipoint injection, same motor as Golf, Audi A3, various Seats etc)

About 10 days ago it started revving up by itself at idle to 4 - 5,000rpm, gearbox in neutral, foot OFF the pedal. It would shut off on the key, and then refuse to restart straight away.

If left for 15 mins or so it will restart and behave normally for a day or so, then repeat the above.

Only does it when warmed up. Runs fine when cold.

No check engine light, and no fault codes on a Skoda dealer's diagnostics nor an independent garage's.

The independent had a look at the throttle body and said there was some muck in there, but not much. Because he couldn't see any fault codes he could only suggest driving it for a bit and see if a code came up.

I'm thinking it's possibly: a) Idle control valve, b) throttle butterfly position sensor, c) MAF or d) Lambda sensor.

Any other suggestions / recommendations please?

Ta.

CrisPDuk

Sounds like idle control to me, or at least that's what the cause was when my Mk2 Golf started doing a similar thing

Of course with modern sensor infested engines a fault with any one of the fuel or air related sensors will cause it Try disconecting, cleaning, and WD40ing* every plug connection you can see on the induction system.


Other lubricants are available

brickboy

Turns out it's the throttle potentiometer that's gone, the pot must have got tracked or grooved, as it's actually pulling / twitching on the throttle cable

EDIT -- nope, it's the coolant temp sensor that's fritzed, the throttle body is actually motorised so if the temp sensor says it's -15 degrees, the throttle will open itself automatically